EP3351781A1 - Method for piloting a powertrain for pollution control of the exhaust line thereof - Google Patents

Abstract

The invention relates to a method for controlling a vehicle powertrain (GMP), the control comprising a first mode (NOx f) and a second mode (CO2 f) of operation, the first mode (NOx f) being less emissive of a pollutant than the second mode (CO2 f), characterized in that, during a first mode (NOx f), it is determined for the current window whether the difference in the quantity of pollutant (”X) at the output of the line with a quantity of target pollutant is lower than a first threshold (a), it is determined whether the sum of these differences (SNOx X) over the successive windows is lower than a second threshold (c) and whether the efficiency of the depollution element (RCS) is considered sufficient to treat the pollutant with the second mode (CO2 f), this is applied at the start of the next current window.

Description

The invention relates to a method for controlling operating parameters of a powertrain, that is to say the engine or engines, the gearbox and the pollution control system for optimizing the emissions of a motor vehicle, particularly nitrogen oxides, while controlling at the best possible level the fuel consumption. This optimization requires a concerted management of engine emissions, called emissions at the source and the after-treatment system of the exhaust line. The piloting according to the present invention is based on an evaluation of the instantaneous depollution efficiency but also on the history of previous depollution efficiencies.

The present invention is therefore part of the technical field of global control of a power train, including but not only its modes of combustion by a powertrain control unit, the powertrain being equipped with a heat engine advantageously Diesel. By operating parameters of the powertrain, it will be understood operating parameters of the engine, mainly combustion parameters and fuel injection.

By operating parameters, it is also understood to be such parameters of parameters relating to auxiliary devices of the powertrain and not only of the engine. Examples of parameters will be given later.

The present invention is applicable to limit the emissions of pollutant from the powertrain to any type of pollutant present in the exhaust gas, but it relates more particularly to the reduction of nitrogen oxide emissions, also known under their NOx chemical formula , a formula that can also be used in what follows. In addition to the reduction of emissions at the source, this depollution is also done through a system of pollution control as but not limited to selective catalytic reduction, also called RCS system, which may also be used in the following.

A selective catalytic reduction system by injection into the exhaust line of a so-called SCR reducing agent, this agent being advantageously but non-limitingly urea or a urea derivative, precursor of ammonia, is used to reduce the nitrogen oxides or NOx present in the gases discharged from the engine by an exhaust line.

Such a system has a control unit capable of estimating or measuring the quantities of nitrogen oxides per second emitted at the output of the engine but also at the exit of the exhaust line. The control unit of the RCS system also calculates a quantity of reducing agent to be injected into the exhaust line according to parameters of the exhaust line and / or combustion parameters in the internal combustion engine. This calculation can be done in open loop.

A SCR system has physical processing limits. It is therefore necessary in certain situations to limit emissions at the source to achieve a NOx emission performance at the end of the exhaust line, in order to guarantee for example the regulatory thresholds, which are more and more restrictive and which may concern both current emissions and a previous range of operation of the vehicle.

In the particular case of diesel NOx, limiting NOx emissions at the source usually leads to a deterioration of the energy efficiency of the power train and therefore increases the fuel consumption of the vehicle. This increase in consumption translates into a similar increase in carbon dioxide emissions, hereinafter also referred to as CO _2, both of which are linked.

The settings of the engine and, for example, of the gearbox, allow a low emissive operation emission of the pollutant considered, for example NOx, and those allowing a sober behavior in fuel consumption have very strong discontinuities and do not allow the application of a simple regulation function between these different states.

The decision rules for switching from a low-NOx mode of operation to a low-fuel and, where appropriate, CO ₂ emission mode of operation are therefore generally calibrated on environmental variables such as, for example, without this being limiting, the speed of the vehicle, the temperature of the engine and of the exhaust line, in particular the temperature of the RCS system.

The problem of the passage between such modes of operation is that it does not allow to find the right compromise between, on the one hand, the respect of vehicle emissions at the exit of the exhaust line on all life situations and, d on the other hand, a minimization of the fuel consumption of said vehicle.

The document FR-A-3 031 764 describes a control method of a powertrain comprising a heat engine connected to an exhaust line in which is disposed a pollution control system of a pollutant present in the exhaust gas emitted by the engine. A powertrain control computer includes in memory several different operating modes of the powertrain. It is determined a pollutant content in the exhaust gases not to be exceeded at the exit of the exhaust line.

For each of the predetermined operating modes, the content of the pollutant produced at the source by the heat engine, the maximum efficiency of pollution control by the pollution control system, the expected content of the pollutant downstream of the pollution control system, from the expected content at the source and the maximum associated depollution efficiency. The estimated levels for each of the predetermined modes of operation are compared to the target grade and one of the operating modes for which the estimated grade is lower than the target grade is used to provide the least fuel consumption.

Therefore, the problem underlying the present invention is to obtain an onboard decision process that allows to choose an optimal mode among the powertrain's discrete operating modes with respect to the emissions of a given pollutant in the exhaust gas at the end of the exhaust line.

• on détermine pour la fenêtre courante, la différence de la quantité de polluant en sortie de la ligne avec une quantité de polluant cible,

on détermine la somme de ces différences sur nombre prédéterminé de fenêtres successives incluant la fenêtre courante,
et, si la différence de la quantité de polluant en sortie de la ligne avec une quantité de polluant cible pour la fenêtre courant est inférieure à un premier seuil, que la somme de ces différences sur le nombre prédéterminé de fenêtres successives est inférieure à un deuxième seuil, et que l'efficacité de traitement de l'élément de dépollution est jugée suffisante pour traiter les émissions du polluant prédéterminé avec le deuxième mode, le premier mode est remplacé au début de la fenêtre courante suivante par le deuxième mode de réglage pour le pilotage des paramètres du groupe motopropulseur, sinon on garde le premier mode pour la fenêtre courante suivante.To achieve this objective, it is provided according to the invention a method of controlling operating parameters of a powertrain of a motor vehicle, in which a monitoring of the emissions of a predetermined pollutant rejected by an exhaust line is performed, this predetermined pollutant being at least partially treated by a depollution element present in the exhaust line, a treatment efficiency of the depollution element being determined, the control being carried out from a first mode and at least one second mode of adjustment of the operating parameters, the first mode being less emissive of this pollutant at the source than said at least second mode, a number of successive windows of determined duration including a current window being fixed for monitoring emissions of the predetermined pollutant, characterized in that, in a first mode,

• for the current window, the difference of the quantity of pollutant at the outlet of the line with a quantity of target pollutant is determined,

the sum of these differences is determined on a predetermined number of successive windows including the current window,
and, if the difference in the amount of pollutant leaving the line with a target pollutant quantity for the current window is less than a first threshold, that the sum of these differences on the predetermined number of successive windows is less than a second threshold, and that the treatment efficiency of the depollution element is considered sufficient to treat the emissions of the predetermined pollutant with the second mode, the first mode is replaced at the beginning of the next current window by the second adjustment mode for the controlling the powertrain parameters, otherwise we keep the first mode for the next current window.

The technical effect is to achieve an optimal compromise in all life situations that depends on the level of performance of the depollution element. If the depollution is correctly ensured and has been in previous windows, the present invention proposes to move to a mode of operation concerning the entire powertrain, that is to say not only the engine but also the auxiliary elements associated with the heat engine, less severe in terms of emission at the source of the pollutant but having advantages in particular on engine performance and therefore fuel consumption, knowing that the overall emissions of the pollutant concerned will remain constant as offset by the efficiency of the post-processing system. The vehicle's drivetrain is therefore optimally suited to specifications concerning, on the one hand, limiting the emissions of a pollutant and, on the other hand, controlling fuel consumption or, where appropriate , a depollution agent, for example based on urea for a SCR system. All of these strategies are done in full respect of current emission regulations.

For this, in order to allow the change of mode it should be verified that the cumulative amount of pollutant at the exit of the exhaust line is well below a threshold, this for the current window. In addition, it is necessary that the first operating mode implemented has not had a negative impact on the maintenance of the total pollutant level at the exit of the required exhaust line over a predetermined duration, for example a running running, that is to say in a duration extending over several windows measurement. If these two conditions are not met, we stay in the mode of operation the least emissive.

In the case where the threshold has been respected both during the current window and for a preceding predetermined duration and including the current window, it is then possible to choose a mode of operation of the transmission unit that is more emissive in terms of the pollutant considered, the efficiency of the pollution control system being able to ensure the achievement of the required threshold. However, it is still possible to return to the initial operating mode if the efficiency of the pollution control system by the replacement mode proves to be insufficient.

Advantageously, when at least three adjustment modes are present, in case of replacement of the first mode, this first mode is replaced by one of at least two other modes the least emissive. As a result, there may be several modes of operation for the powertrain as a whole and for the heat engine forming part of the powertrain, varying from a mode that is less emissive to the source, when the efficiency of the pollution control system is low. to progressively more emissive modes at the source, when the efficiency of depollution is high, these modes favoring in particular the fuel consumption of the engine. The mode replacements can therefore be done gradually by adopting the best NOx / CO ₂ compromise in compliance with the regulations in force.

Advantageously, during one of the modes other than the first mode, when the difference in the quantity of pollutant leaving the line with the quantity of pollutant target is less than the first threshold for this mode other than the first mode, the mode other than the first mode is maintained. The measurement on the current window shows that the other mode then in use is sufficient to maintain the amount of pollutant at the exit of the exhaust line below the target quantity: the pollution of the gases by polluting at the exit of the exhaust line is then still optimally ensured even with this mode more emissive than the first mode.

Advantageously, during this other mode, when the difference in the quantity of pollutant leaving the line with the quantity of target pollutant is greater than the first threshold, a summation is made of the quantities of pollutant released on a predetermined number of successive windows and when the difference in summation of the amounts of pollutant with the total amount of target pollutant for these windows is less than the second threshold, the other mode is retained while, when the difference in the summation of the quantities of pollutant with the total amount of target pollutant for these windows is greater than the second threshold, the first mode is reestablished.

If, for a current window, the emission levels of the pollutant do not fulfill the required criteria, it is examined whether, over a certain period corresponding to a number of windows, the effectiveness of the depollution has been generally ensured. If this is the case, the less severe mode in terms of emissions at the source that the first mode is maintained. If this is not the case, return to the first mode to ensure that the required level of pollutant is reached.

Indeed, in the exhaust line of a combustion engine, in particular Diesel, it is common to have a probe specifically dedicated to the pollutant downstream of the depollution element by referring to the path of the gases in the line d. 'exhaust. It is then possible to know if the pollutant quantity target at the output of the fixed line was held for the current window and since the beginning of the rolling, this being done by integrating the various quantities of pollutant for the successive windows. It is the respect of the target value of pollutant rejected over a long interval which prevails even if this respect is not ensured for a current window.

If this is not the case, the first mode becomes the current mode and it is switched to a combination of combustion mode and various levers of the less emissive powertrain while polluting at the source with the disadvantage of being less sober in consumption. of fuel, since the first priority of the vehicle is compliance with the pollutant emission standard and therefore the target quantity of pollutant rejected for the window or the successive windows.

Otherwise, the second mode is retained but when at least three modes are available, it can then also be considered the opportunity to switch to an even more sober mode of fuel consumption, the effectiveness of the pollution control system being able to ensure that the required pollutant emission threshold is reached.

The present invention has made this transition less risky than previously made by the state of the art by making this transition gradual and by monitoring the effect of this transition on the quantities of pollutant discharged into a window or in the duration of several windows by relative to the target quantities. It is then easier to select the mode that optimizes both the depollution and the consumption of fuel or return to a mode that continues to ensure the level of pollution at the expense of consumption.

Advantageously, the predetermined number of successive windows is the number of windows since a beginning of the current running.

Advantageously, the operating parameters of the adjustment modes relate individually or in combination the management of the laws of passage of the powertrain, the management of energy samples taken on the powertrain, combustion modes of the engine.

Advantageously, said at least one second mode results in a decrease in the release of carbon dioxide into the exhaust line and a reduction in fuel consumption by the engine.

Advantageously, the first and second thresholds are equal to zero. It is indeed necessary to remain the closest to the target values of quantity of pollutant at the exit of the exhaust line.

The invention also relates to a power unit of a motor vehicle comprising a heat engine and its auxiliary elements including an exhaust line comprising at least one means of pollution of a rejected pollutant and means for measuring or estimating the pollutant downstream of the pollution control element, the engine and the auxiliary elements of the powertrain being controlled by a control unit comprising means for memorizing at least two modes of adjustment of the operating parameters of the powertrain and means of calculating a target quantity of rejected pollutant, characterized in that the control unit has control means for comparing the current and target pollutant quantities over a plurality of time intervals and means for implementing such a pollutant process. control of operating parameters of a power train.

Such a powertrain is driven relative to a target amount of pollutant, for example NOx, taken at the outlet of the exhaust line to meet the requirements of the standards in force. The quantity of effective pollutant at the outlet is measured, this by a sensor specifically dedicated to the pollutant, or estimated. By having measurements or emission estimates at the source of the current mode and other modes of operation, as well as the maximum efficiency achievable, it is then possible to choose the most optimal operating mode to reach the pollutant target at the outlet of the exhaust line while minimizing the fuel consumption and, where appropriate, reducing agent injected into the line for the neutralization of the pollutant considered.

Advantageously, the pollutant is in the form of nitrogen oxides and the depollution element is a selective catalytic reduction system.

• la figure 1 est une représentation schématique d'un groupe motopropulseur et d'une ligne d'échappement avec mention de divers modes de fonctionnement du groupe motopropulseur et du moteur thermique favorisant plus ou moins soit l'émission des NOx ou soit l'émission du CO2, le procédé de pilotage de paramètres de fonctionnement d'un groupe motopropulseur selon la présente invention pouvant être mis en oeuvre pour un tel groupe motopropulseur,
• la figure 2 montre un logigramme d'un mode de réalisation du procédé de pilotage de paramètres de fonctionnement d'un groupe motopropulseur selon la présente invention.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows and with reference to the appended drawings given by way of non-limiting examples and in which:

• the figure 1 is a schematic representation of a powertrain and an exhaust line with mention of various modes of operation of the powertrain and the heat engine promoting more or less the emission of NOx or CO2 emission, the method for controlling operating parameters of a powertrain according to the present invention that can be implemented for such a powertrain,
• the figure 2 shows a flowchart of an embodiment of the driving method of operating parameters of a powertrain according to the present invention.

It should be borne in mind that the figures are given by way of examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily at the scale of practical applications.

In what follows, reference is made to all the figures taken in combination. When reference is made to one or more specific figures, these figures are to be taken in combination with the other figures for the recognition of the designated reference numerals.

What is meant by powertrain means the engine but also auxiliary devices such as an air intake line, a recirculation line of the gas at the intake of the engine, a turbocharger, an exhaust line with one or more depollution elements which can be controlled for example the amount of reducing agent added in the line or its temperature, a gearbox with its passing laws and an engine cooling circuit with respect to relates to the management of the temperature of the cooling fluid. This list is not exhaustive.

It will be taken as an example in what will follow a depollution of nitrogen oxides in the exhaust line, by a RCS system. This is not limiting and the present invention may concern a depollution of another pollutant or an NOx decontamination by a system other than a RCS system, in particular an active or passive nitrogen oxide trap, the temperature and the temperature. injection of fuel into the exhaust line then playing an important role in the destruction of NOx.

Referring to the figures, the present invention relates to a method for controlling the operating parameters of a motor vehicle power unit GMP. These parameters may relate to the combustion of the thermal MTH engine of the GMP powertrain, in particular the fuel injection and the air intake but also the management of the depollution in the exhaust line of the exhaust gases of the MTH engine or the management of the output transmission of the MTH engine.

In this method, monitoring of the emissions of a predetermined pollutant released by an exhaust line of the motor vehicle is carried out, this predetermined pollutant, here NOx, being at least partially treated by a depollution element RCS present in the line d 'exhaust.

With particular reference to the figure 2 , the control is carried out from a first mode NOx f and at least a second mode CO2 f of adjustment of the operating parameters. The first mode NOx f is able, in cooperation with the depollution element RCS, to maintain a quantity of this predetermined pollutant at the exit of the exhaust line in relation to a target quantity of this pollutant. Said at least a second mode CO2 f implies quantities of this predetermined pollutant emitted at the source greater than the quantities emitted in the first mode NOx f. It follows that the first mode NOx f is more favorable, when the efficiency of the SCR depollution element is limited, to the pollution of the pollutant than said at least a second mode CO2 f.

To the figure 1 , it is shown for a GMP powertrain three modes of operation G0, G1 and G2 that achieve the required emission level. The G0 mode, which is less emissive to the pollutant predetermined at the source, is adopted when the efficiency of the depollution element RCS is limited for example to NOx, to the detriment of fuel consumption and with emission of another pollutant. , right here of CO2, high. The mode G1 is less efficient than the mode G0 with regard to the emissions at the source of the predetermined pollutant, but more efficient with respect to the emission of the other pollutant, CO2. It is adopted when the effectiveness of the SCR element is good while not achieving its optimum performance. The G2 mode further reduces fuel consumption and CO2 emissions compared to the G1 mode while still achieving the required level of NOx decontamination, the efficiency of the RCS decontamination element being optimal. The parallel arrows crossing the GMP group horizontally show emissions at the source increasing inversely for NOx and CO2, the + and - respectively indicating the strongest and weakest emissions of the pollutant considered, this at the output of the engine from where the name of NOx source.

These modes can relate to pollution control management parameters, gearbox transmission laws and thermal regulation that can be adapted to not be the most efficient with respect to engine performance but causing less emissions. pollutant. On the other hand, the operating modes of the engine are linked in any order according to the overall emissions of the vehicle from the required level.

It can also be carried out with additional fuel injections, for example to heat the pollution control element at the beginning of taxiing of the vehicle, in particular post-injections of fuel. The cooling system of the engine can also be adjusted to reduce emissions of the pollutant.

The figure 1 also shows schematically a heat engine MTH with the possibility of inclusion of five combustion modes, essentially concerning injection parameters, including the amount of fuel injected and / or times and the number Z of injections. The M0 mode increases the performance of the RCS decontamination element and the M1 mode minimizes emissions at the source while the M4 mode minimizes fuel consumption. Modes M2 and M3 are intermediate modes that conserve fuel and produce NOx at the source. The source CO2 and NOx arrows are also present to show the evolution of the emissions of these two pollutants as a function of the modes M0 to M4 at the engine output.

In the depollution element that is in the example of the figure 1 a system of injection of reducing agent into the exhaust line, more precisely a SCR system, the injection of reducing agent is controlled so as to maximize the efficiency performance of the SCR system, the reducing agent being advantageously urea.

For tracking the target target quantity of NOx rejected at the end of the exhaust line, the running time is divided into predetermined successive evaluation duration windows. The efficiency of the RCS system is also determined by estimation or measurement.

According to the invention, with particular reference to the figure 2 during the first NOx mode f primarily favoring the reduction of the pollutant treated at the source, for example NOx, for a current evaluation window, when a difference in the quantity of pollutant ΔX at the end of the line with the quantity of pollutant target is less than a first threshold a, it is carried out a summation of the amounts of pollutant SNOx rejected during a predetermined number Z of successive windows. This attests that for the current window, the pollutant depollution instruction is respected or is close to being according to the first predetermined threshold a. It is then checked if this is the case for the previous windows added to the current window.

When the difference of the SNOx summation X of the pollutant quantities SNOx with the total quantity of target pollutant for these windows is less than a second threshold c, the first mode NOx f is replaced by the second mode CO2 f of adjustment for the control of the GMP powertrain settings. This proves that over the long term cleanup has been ensured and that it is possible to envisage a more favorable mode of operation in terms of consumption, the depollution element RCS having the capacity to treat the NOx emissions at the source more high.

As shown in particular figure 1 there may be at least three adjustment modes. If the conditions set out above allow it, and the treatment efficiency of the pollution control element is considered sufficient to treat the emissions of the predetermined pollutant with the second mode, the first mode NOx f can be replaced by another estimated CO2 mode f able to comply with at least the second threshold c for the summation of the amounts of pollutant SNOx released, advantageously one of the at least two other intermediate modes CO2 f NOx emission at the source, so that the transition from one mode to another is progressively to ensure long-term compliance with the required level of pollutant emissions.

One or more windows can be expected to check whether this other mode CO2 f can be replaced by another mode CO2 f even more efficient in terms of consumption and so on, to validate the ability of the depollution element RCS to treat the extra NOx at the source and gradually lead to the optimized operating mode both in emission and fuel consumption.

The figure 2 illustrates an embodiment of the method for controlling operating parameters of a GMP powertrain. Starting from a mode that is most favorable to emissions at the source referenced NOX f, a number Z of windows is defined. A question is then asked as to whether a difference ΔX of the quantity of pollutant leaving the line with the quantity of target pollutant is lower than a first threshold a, which is referenced ΔX <a.

If the answer to this questioning is no, symbolized by N at the figure 2 he returned to Z = 0. If the answer to this questioning is yes, symbolized by O at the figure 2 , it is counted the window with other windows so that Z goes to Z + 1. When a difference in the quantity of pollutant ΔX at the exit of the line with the quantity of pollutant target is lower than a first threshold a, it can therefore be carried out a summation of the amounts of pollutant SNOx rejected during a predetermined number Z of successive windows. This attests that for the current window, the pollutant depollution instruction is respected or is close to being according to the first predetermined threshold a.

If Z is greater than or equal to a threshold of windows b, ie Z ≥ b, which is represented by the output O of this interrogation, a summation is made of the amounts of pollutant SNOx rejected during a predetermined number Z of successive windows. The window threshold b may be a threshold corresponding to the number of windows of the current running. The threshold b is advantageously calibrated.

If the difference SNOx X of the summation of the quantities of pollutant SNOx with the total quantity of target pollutant for these windows is less than a second threshold c, which is illustrated by the output O of the SNOx questioning X <c, if the efficiency for the treatment of the depollution element RCS is considered sufficient to treat the emissions of the predetermined pollutant with the second mode CO2 f, the first mode NOx f is replaced by another mode CO2 f of adjustment for controlling the parameters of the powertrain GMP , at the beginning of the next current window. This other mode CO2 f is less advantageous in terms of emission at the source of NOx, but the depollution remains optimal because the efficiency of the depollution element RCS makes it possible to treat the excess of NOx.

The dotted lines symbolize a preferred embodiment of the present invention which shows a possible return of the other mode CO2 f to the first mode NOx f if the required emission level of NOx can no longer be achieved with the efficiency expected of the SC depollution element, or a maintenance of this other mode CO2 f otherwise.

During one of the modes CO2 f other than the first mode NOx f, when the difference of the quantity of pollutant ΔX at the exit of the line with the quantity of target pollutant is lower than the first threshold a for this mode other than the first mode NOx f , the mode other than the first mode NOx f is maintained. It ensures in fact a sufficient depollution for this window. It is returned by the dotted line O for yes starting from ΔX <a to return to CO2 f.

Conversely, during this other mode CO2 f, when the difference of the quantity of pollutant ΔX at the end of the line with the quantity of pollutant target is greater than the first threshold a, it is carried out a summation of the quantities of pollutant SNOx rejected on a number Z predetermined successive windows. This is shown by the dotted line N for diagonal not due due ΔX <a to SNOx X <c.

The first and second thresholds c, c can be calibrated and can be zero so that the amounts of pollutant can be equivalent to the target quantities of pollutant so that the depollution follows more closely the target target.

When the difference of the SNOx summation X of the pollutant quantities SNOx with the total quantity of target pollutant for these windows is lower than the second threshold c, the other mode CO2 f is retained. This is illustrated by the dashed line O for yes starting from SNOx X <c to CO2f.

When the difference of the SNOx summation X of the quantities of pollutant SNOx with the total quantity of target pollutant for these windows is greater than the second threshold c, the first NOx mode f is reestablished. This is illustrated by the dashed line N for no from SNOx X <c to NOx. The predetermined number Z of successive windows may be the number Z of windows since a beginning of the current running.

The operating parameters of the adjustment modes may concern, individually or in combination, the management of the passing laws of the GMP powertrain, the management of the energy samples taken on the GMP powertrain, the combustion modes of the thermal MTH engine.

Said at least a second mode CO2 f can be chosen to cause a reduction of carbon dioxide discharge in the exhaust line and a reduction in fuel consumption by the thermal MTH engine.

The invention also relates to a powertrain GMP of a motor vehicle comprising a thermal MTH engine and its auxiliary elements including an exhaust line comprising at least one means of decontaminating a rejected pollutant and measuring or estimating means pollutant downstream of the SCR depollution element. Examples of auxiliary elements have been previously mentioned.

The MTH engine and the auxiliary elements of the GMP powertrain are controlled by a control unit comprising means for storing at least two modes NOx f, CO2 f for setting operating parameters of the powertrain GMP and calculation means a target quantity of pollutant released.

According to the invention, the command control unit comprises means for comparing the current and target pollutant quantities over a plurality of time intervals, in particular on the current window and a series of previous successive windows, advantageously since the beginning of the current rolling. . The control unit comprises means for implementing such a method for controlling operating parameters of a GMP powertrain.

In a preferred application of the present invention, the pollutant is nitrogen oxides and the depollution element is a selective catalytic reduction system with injection of reducing agent in the form of urea.

In this case, the urea injection of the SCR system can be calibrated in such a way as to maximize the efficiency of the SCR element or to control the urea consumption while maintaining the NOx emission of the SCR. vehicle to the required level by adaptation of emissions to the engine source.

The method according to the invention makes it possible to guarantee an operating mode adapted to each life situation, to reach the regulatory emission targets, to minimize the fuel consumption and, where appropriate, the consumption of depollution agent. The method according to the invention makes it possible to guarantee the durability of the components of the depollution element, advantageously a RCS post-treatment system.

For the car manufacturer, it is obtained a reduction of the costs engendered by possible returns of a vehicle under warranty in after-sales and an improvement of the perception of the reliability of the vehicle by the driver hence an improvement of the image manufacturer's mark.

The invention is in no way limited to the described and illustrated embodiments which have been given by way of example only.

Claims (10)

A method for controlling operating parameters of a motor vehicle power unit (GMP), in which a monitoring of the emissions of a predetermined pollutant rejected by an exhaust line is performed, said predetermined pollutant being at least partially treated by a depollution element (RCS) present in the exhaust line, a treatment efficiency of the pollution control element (RCS) being determined, the control being carried out from a first mode (NOx f) and at least a second mode (CO2 f) of adjustment of the operating parameters, the first mode (NOx f) being less emissive of this source pollutant than said at least second mode (CO2 f), a number (Z) of successive windows of determined duration including a current window being fixed for monitoring emissions of the predetermined pollutant, characterized in that , in a first mode (NOx f), for the current window, the difference in the quantity of pollutant (ΔX) at the outlet of the line with a quantity of target pollutant is determined, the sum of these differences (SNOx X) is determined on a predetermined number (Z) of successive windows including the current window, and, if the difference of the pollutant quantity (ΔX) at the exit of the line with a target pollutant quantity for the current window is less than a first threshold (a), than the sum of these differences on the number (Z) predetermined number of successive windows is less than a second threshold (c), and that the treatment efficiency of the depollution element (RCS) is considered sufficient to treat the emissions of the predetermined pollutant with the second mode (CO2 f), the first mode (NOx f) is replaced at the beginning of the next current window by the second mode (CO2 f) of setting for controlling the parameters of the powertrain (GMP), otherwise we keep the first mode (NOx f) for the window following standard. Method according to the preceding claim, wherein, when at least three adjustment modes are present, in case of replacement of the first mode (NOx f), this first mode (NOx f) is replaced by the least emissive of the at least two other modes (CO2 f). Method according to one of the two preceding claims, wherein during one of the modes (CO2 f) other than the first mode (NOx f), when the difference in the quantity of pollutant (ΔX) at the end of the line with the quantity of target pollutant is lower than the first threshold (a) for this mode (CO2 f) other than the first mode (NOx f), the other mode (CO2 f) that the first mode (NOx f) is maintained. Process according to the preceding claim, in which, during this other mode (CO2 f), when the difference of the quantity of pollutant (ΔX) at the outlet of the line with the quantity of target pollutant is greater than the first threshold (a), it a summation of the quantities of pollutant (SNOx) discharged over a predetermined number (Z) of successive windows and, when the difference of the summation (SNOx X) of the quantities of pollutant (SNOx) with the total quantity of target pollutant for these windows is lower than the second threshold (c), the other mode (CO2 f) is retained while, when the difference of the summation (SNOx X) pollutant amounts (SNOx) with the total amount of pollutant target for these windows is greater than the second threshold (c), the first mode (NOx f) is restored. A method according to any one of the preceding claims, wherein the predetermined number (Z) of successive windows is the number (Z) of windows from a beginning of the current running. A method according to any one of the preceding claims, wherein the operating parameters of the control modes relate individually or in combination the management of the laws of passage of the powertrain (GMP), the management of the energy samples taken on the powertrain (GMP ), the combustion modes of the engine (MTH) thermal. A method as claimed in any one of the preceding claims, wherein said at least one second mode (CO2 f) results in a decrease of carbon dioxide discharge in the exhaust line and a reduction in fuel consumption by the engine (MTH ) thermal. A method as claimed in any one of the preceding claims, wherein the first (a) and second thresholds (c) are equal to zero. Powertrain (GMP) of a motor vehicle comprising a thermal engine (MTH) and its auxiliary elements including an exhaust line comprising at least one means of decontaminating a rejected pollutant and means for measuring or estimating the pollutant downstream of the pollution control element (RCS), the engine (MTH) and the auxiliary elements of the powertrain (GMP) being controlled by a control unit comprising means for memorizing at least two modes (NOx f, CO2 f) for adjusting the operating parameters of the powertrain (GMP) and means for calculating a target quantity of rejected pollutant, characterized in that the control unit has means for comparing the quantities of current and target pollutant over several time intervals and means for implementing a pollutant process. control of operating parameters of a powertrain (GMP) according to any one of the preceding claims. Powertrain (GMP) according to the preceding claim, wherein the pollutant is in the form of nitrogen oxides and the depollution element is a selective catalytic reduction system.

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